This project has two major investigational thrusts. The first deals with demented patients' ability to function in daily life. This involves both rating of functional capacity by collateral sources (spouse, child, etc.) and actual measurments of function in simulated activities of daily living. The result of these measures will be compared to the biological findings (PET, CAT, etc.) and to the more laboratory style of cognitive testing carried out by Dr. Botwinick, especially with respect to how these factors change over the course of the longitudinal project. The second area of research deals with the effect that demented patients' problems have on their primary caregivers (i.e., family burden). A number of measures of perceived burden and emotional stress obtained from the caregivers will be related to the patients' functional abilities, as well as to other investigators' measures of biological and cognitive decline.